1. Field of the Invention
The invention concerns the steerable movement of a load such as a container or a pallet between areas in which it must in principle be set down directly, without the intermediary of any wheels, and in an accurate position. It is more particularly concerned with the unaided manipulation of medium-weight containers (typically weighing in the order of several hundred kilos) containing munitions or hardware to be slung underneath an aircraft, for example.
2. Description of the Prior Art
The handling means currently employed for unaided manual movement of containers are usually respective dollies mounted at the front and the rear of the container which simultaneously support and move the container.
Usually one of the dollies is steerable while the other is not. Accordingly, during movement of the container and especially during its final approach to a precisely defined position (for example, under part of an aircraft to which the content of the container is to be attached), it is necessary to carry out a large number of maneuvers with many turns, the larger the turning circle the greater the number of such maneuvers. As a result, positioning is time-consuming and laborious.
What is more, moving containers and loads in various locations, for example store rooms, hangars, elevators, aircraft carrier flight decks, with obstacles to circumvent (especially single or double ramps) in practice requires dedicated handling means in order to comply with applicable safety standards. In particular, it is necessary to ensure stability to prevent tilting which places a limit on the turning circle and, preferably, to immobilize the load during movement in the event of the operatives losing control of the load. There is also the need to have multipurpose equipment in order to reduce the total number of handling means to be kept in availability.
An object of the invention is therefore to provide a removable dolly for steerable movement of a load which is adapted to cooperate in a simple manner with the load in order to lift and move it, which provides a large turning angle for a small maneuvering angle (typically 50.degree. for a turning angle of 70.degree.), while guaranteeing high stability of the load in movement, even in the maximum turning configuration (including the situation in which, when the load is provided at each end with a removable dolly for steerable movement, with both dollies in the maximum turning configuration), requiring the load to be lifted through a small distance to its movable position, which advantageously allows for an immobilizing system either in the movable position (load stationary) or in the event of the operatives losing control of the load (dropping the load, for example), and all this from a simple and rugged structure.
French Patent Nos. 2,597,807 and 2,647,731 disclose a handling/moving device intended to be mounted on wheels and adapted to lift one end of a container so that it can be moved. The device includes an apron with means for removably fixing it to one side of the container, a chassis mounted on an axle pivoting about a vertical axis, the carriage sliding along this chassis and being articulated to the apron, and a jack system articulated to the apron and to the chassis to control their relative inclination. In use this device is attached to the container and then the jack system is actuated to lift the end of the container and then to slide under this end of the container the part of the chassis to which the axle is pivoted.
This device is not a satisfactory solution to the technical problem mentioned above in that, firstly, it does not provide a large turning angle without compromising the stability of the container (the farther the axle is turned the greater the risk of tilting sideways) and, secondly, it requires a source of hydraulic power. Finally, there is nothing to guarantee immobilization of the load in the event of the operatives losing control while the load is moving. Also, the pivots between the chassis and the apron are heavily loaded during lifting and lowering which is prejudicial both to their stiffness and to the ruggedness of the combination. Note that this document is not concerned with manual movement but rather with motorized movement since it requires an auxiliary motive power source (see above) and is directed to the provision of a road transport system capable of travelling at speeds in the order of 100 kph.